1. Field of the Invention
The present invention relates generally to a system for mounting and installing photovoltaic solar panels, and more particularly, to a mounting support system that can be rapidly constructed on a large scale.
2. Description of the Related Art
Solar photovoltaic (PV) cells convert light directly into electricity. By utilizing the most abundant, renewable energy available on the planet, namely the sun's rays, PV cells can provide a non-polluting source of electrical energy. As global energy consumption rises the need for clean, renewable sources of power has increased tremendously. This combined with the increased costs of conventional, fossil fuel based energy sources has led to a new era where solar PV systems can generate electricity at market competitive rates on a per kilowatt-hour basis.
The rapid adoption, development and construction of PV based power plants has led to greater and greater market opportunities for companies producing PV modules. A PV module is an assembly of solar PV cells, typically in a glass laminate which is contained in a frame composed of aluminum or other metal. The PV module acts as an electrical component of a system of many such modules. Thousands of modules are strung together electrically to form commercial arrays for the generation of many thousands of kilowatts, or ‘megawatts’ of power. The greatly expanded market for PV modules combined with federal, state and local government incentive programs as well as huge investments in production capacity has created tremendous competition among PV module manufacturers. This competition has resulted in PV modules that now retail for as little as $1.00 per watt capacity at peak power output of the module. This compared to PV module prices of $4-$5 per watt just a few years ago.
The rapid decrease in PV module costs in combination with the desire on the part of electrical utilities to own renewable energy assets has led to a renewed focus on so-called, ‘balance of system component’ costs. These components include DC-AC inverters, electrical connection components, and the racking systems used to hold the PV modules in place and exposed to the sun's rays. The racking systems must present the modules to the sun at a favorable degree of tilt while maintaining their structural capacity for 20 to 30 years which is the warranted energy production lifetime of the PV modules.
The racking systems used for PV modules are often referred to as mounting structures. These systems are typically composed of metal, usually steel or aluminum. The systems have an element that is placed in the ground or attached to large ballast blocks typically of concrete. From this post or pier the system stands in the air supporting the PV modules at a height that is appropriate to prevent ground cover, encroaching weeds, or blown up topsoil from affecting the light exposure of the modules but not so tall as to require excess building materials. The primary structural load on these systems is created by wind forces acting on the PV modules themselves. The mounting systems present the modules to the wind in a manner not unlike a sail boat holds a sail—thus great amounts of wind load can be present in a typical PV system.
As PV module mounting systems are deployed for larger and larger ground based systems the need to reduce the costs of the system through better engineering, reduction in total materials required and the innovative use of standardized commercial construction elements continues to rise. The costs and time associated with actual construction of the systems is also the subject of intense scrutiny as commercial building contractors look to be more and more competitive in the installation and commissioning of commercial and utility based PV power systems.
The overall ease with which a PV mounting system can be delivered to the construction site, assembled, installed and finally commissioned is referred to in the PV power industry as ‘constructability’. There are many factors that play into good constructability, among them the reduction in labor hours required to assemble the system or the elimination of special trades and skills being required to complete the assembly. The elimination or reduction in special tools or expensive equipment needed is also a good step toward better constructability. Finally the ability to install the mounting systems in many differing climates, types of terrain, and in naturally occurring hazards such as wind, rain or snow can be the key to a suitable design for low cost, high value PV power systems.
From these requirements for good constructability it can be understood that a PV mounting system which reduces the field labor hours required to build it and that eliminates costly, highly skilled trade workers would be desirable. A mounting system that can be assembled without the use of specialized tools or expensive and difficult to place equipment, such as cranes and hoists, would also be beneficial. Furthermore a system which can be sited on uneven terrain and made level through a series of minor adjustments, both to the height of the modules and the tile angle of the assembly, would allow for an assembly sequence with fewer steps. And lastly a PV mounting system that has at its core a utilization of readily available components that can take advantage of already high production quantities in industry would lead to lower costs for structural elements and thus be a substantial improvement over specialty componentry produced of expensive materials in small quantities unable to reach commercial market cost requirements.